The radio communication technology is faced by a problem of a lack of frequency resources due to recent rapid increase in data traffic. One of examples of major solutions to use frequency resources efficiently is to introduce a relay station. A relay station relays traffic for a terminal located inside a cell or in the vicinity thereof where radio waves are weak (e.g., behind a building, inside a building, or near a cell edge). The usage efficiency of frequency resources can be improved by a relay station reusing frequency resources assigned by a radio communication system for relay.
Patent Literature 1 below discloses a technique in which a relay station relays traffic in accordance with a schedule decided by a base station.